package com.hspedu.newData.dmsxl.树.二叉树的遍历.层序遍历迭代法.队列;

import com.hspedu.newData.dmsxl.ds.TreeNode;
import org.junit.Test;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;

/**
 * @Author: yh
 * @description: 
 * @CreateTime: 2025-04-23 
 * @Version: 1.0
 */

public class LC107二叉树的层序遍历Ⅱ {

    List<List<Integer>> result = new ArrayList<>();

    //
    public List<List<Integer>> levelOrderBottom(TreeNode root) {
        if (root == null) return result;
        Queue<TreeNode> queue = new LinkedList<>();

        queue.offer(root);
        
        while(!queue.isEmpty()){
            ArrayList<Integer> list = new ArrayList<>();
            int len = queue.size();
            
            while(len>0){
                TreeNode node = queue.poll();
                list.add(node.val);
                
                if (node.left!=null) queue.offer(node.left);
                if (node.right!=null) queue.offer(node.right);
                
                
                len--;
            }
            result.add(list);
        }

        List<List<Integer>> result1 = new ArrayList<>();
        for (int i = result.size() - 1; i >= 0; i-- ) {
            result1.add(result.get(i));
        }
        return result1;
    }


    @Test
    public void test() {
        // 测试代码

        TreeNode t7 = new TreeNode(7);
        TreeNode t6 = new TreeNode(6);
        TreeNode t5 = new TreeNode(5);
        TreeNode t4 = new TreeNode(4);
        TreeNode t3 = new TreeNode(3,t6,t7);
        TreeNode t2 = new TreeNode(2,t4,t5);
        TreeNode t1 = new TreeNode(1,t2,t3);

        levelOrderBottom(t1);
        System.out.println("==========");

    }
}
